Introduction: The Lightning Machine: How to Build a Tesla Coil

Have you ever wanted the power to create a lightning storm in your house? Have you ever wanted to build the famous machine in the movies that creates giant sparks that jump into the air? If you have, then you are in luck! About 128 years ago, genius inventor Nikola Tesla invented a machine that could produce giant sparks as well as a powerful radio frequency field. I have created a way to build a professional looking coil easily and cheaply at home. This instructable will show you how to build a Tesla coil that really works. The video below will accompany this instructable with visual demonstrations of the coil as well as additional help building it.

Lets Get Started!!

Step 1: How a Tesla Coil Works

A Tesla coil is relatively simple in its functionality. A Tesla coil has 5 basic components: a high voltage power supply, an adjustable spark gap, a capacitor, a small primary coil, and a large secondary coil. When the high voltage power supply is activated, it produces a high voltage current. This current flows through the primary coil through the capacitor, charging it up. This current flow builds up a large magnetic field in the primary coil. When the capacitor is charged, the voltage across the power supply will be high enough to be above the breakdown voltage of the air in the spark gap. The gap will discharge causing the capacitor to discharge through the secondary coil in the opposite direction. This reverse current flow creates a magnetic field around the primary coil in the opposite direction, collapsing the initial field. This constant changing of field direction happens about 100 times per second, depending on the voltage, capacitance, and spark gap. This fluctuating field induces a current in the secondary coil, and because it is more turns than the primary coil, it produces a voltage which is proportional to the winding ratio. This allows the coil to create over a half of a million volts. The secondary coil also resonates at the frequency determined by the inductance and parasitic capacitance of its windings. Now to building this device.

Step 2: Materials

For this project, you will need a few materials that can be made cheaply.

You will need:

  • Plywood
  • Wire Nuts
  • 2 inch PVC pipe.
  • 16 gauge multi stranded wire
  • Wheels
  • A high voltage power supply(This was build for under $10 from TV parts, Video below)

Step 3:

For this project, you only need a few household tools.

You will need:

  • Drill with drill bits
  • Hot glue gun with glue
  • Hacksaw
  • Screwdriver
  • Jig saw
  • Variac

Step 4: Building the Spark Gap

To build the spark gap, you will first need to take a piece of 2 inch pvc pipe, and cut out a 2 inch section of it. Use a hacksaw. Then, use a drill to make a hole on either side of the section of pipe. The holes should be slightly smaller than the diameter of the threaded bolts you will be using. After the holes are drilled, thread the bolts into each hole until there is a gap between them that is about 1/8 inch. Don't worry about making this perfect now, it can be adjusted later.

Step 5: Building the Base

The base of the Tesla coil will be built out of plywood. It needs to be about 10 inches by 10 inches to hold all the components. To do this, take a sheet of plywood, and use a jigsaw to cut out this square. Make sure to save the scraps of wood, they can be used in a later step.

Step 6: Attaching the Secondary to the Base

To attach the secondary coil to the base, take some of the scraps of plywood from the previous step, and build an insert that will fit into the piece of pipe that will be the secondary coil. This can be made by gluing pieces of wood and Popsicle sticks together until the insert can fit snugly into the pipe. Then, use a drill to make a hole in the center of the base, and screw the insert into it. The secondary should be able to fit over it without wobbling.

Step 7: Adding Wheels

This step is optional, but I think wheels make a Tesla coil look more professional. To add wheels, take them from a trashed set of drawers, and use a drill bit to make a hole in each corner. This hole should be the size of the cylinder on top of the wheel. You can then insert the wheels into the holes. The base should be able to roll freely.

Step 8: Experimenting With Secondary Coils

The secondary coil is a very important part of the coil. It could take a lot of experimenting to get perfect. I experimented with pancake coils and vertical coils. I found a five turn secondary coil around a 3 inch diameter piece of cardboard to be optimum. You can experiment with different types and sizes of coils to find the best result. You can then glue down the piece of cardboard to the base and tape the windings in place.

Step 9: Creating the Capacitor Rack

The capacitor rack will hold the high voltage capacitors in place on the base. It also keeps them insulated from each other. To build this rack, take some of the plywood scraps, and glue them together in a way that hold them tightly in place.You can also use Popsicle sticks. You can build this rack in different ways depending on the materials you have on hand.

Step 10: Wiring the Tesla Coil

To wire the Tesla coil, follow the schematic that I made above. Use connecting wire and wire nuts to connect everything together. Use alligator clip wires to connect the Tesla coil to the power supply. Make sure to wire the capacitors correctly.

Step 11: Adding the Top Load

The top load of the Tesla coil is a piece of metal that the sparks discharge from. It also acts to create a parasitic capacitance that allows the coil to resonate. You can experiment with many different types of top loads. These can be a pie tin, a donut shaped piece of metal, or a simple metal rod. I found a small metal rod to work the best, but you can experiment with different top loads to obtain the best result.

Step 12: It Works!

The Tesla coil should work now. Make sure to use a variac when running this coil. You now have a lightning storm in your room in the form of a Tesla coil. This coil can be used a science demonstration and a source of awesome pictures. You can use this to make awesome arcs in the air. To know how to take the awesome pictures as seen above, stay tuned for my next instructable. Make sure to vote for me in the epilogue contest!

Thanks for reading and good luck building!

Disclaimer: This project deals with very high and potentially fatal voltages and currents. Build this project at your own risk. Always use caution when dealing with high voltage.


Battle Man (author)2016-12-31

is it possible to make a smaller version but still have the same voltage?

zposner (author)2016-12-12

Love lightning and machines

Jfieldcap (author)2016-11-29

You aren't part of an FTC team, by any chance? (I'm noticing your use of Tetrix for winding the coil)

tanner_tech (author)Jfieldcap2016-11-29

I am indeed. I was wondering when someone would notice that.

Jfieldcap (author)tanner_tech2016-11-30

Well, so am I. Good luck with with this year's game!

JasonH132 (author)2016-11-29

Awesome project, very interesting and well done.

I don't think I''ll try play with high voltage stuff. Too scary. Just a safety tip to mention to people... don't experiment with electrical projects on a carpeted floor. You risk burning your house down if something goes wrong ;)

bpark1000 (author)2016-11-29

Your comment about "experimenting with the secondary", but your illustrations show experimenting with the primary.

tanner_tech (author)bpark10002016-11-29

Oops, must have been a typo. it is primary. Thanks for letting me know!

Gadget93 (author)2016-11-29

How does the distance of the spark gap affect things in this tesla coil?

Noodle Lord (author)2016-11-29

Thank you for making a tesla coil, and knowing about tesla. He needs more supporters, go to

Gadget93 (author)Noodle Lord2016-11-29

Thumbs up!!!